Electrical apparatus.



T. F. CROGKER. ELECTRICAL APPARATUS. APPLIGATION FILBDSEH. 18, 1911.

1,037,447. Patented sept. 3,1912

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THOMAS r. cnooxnn., or Darren, cinco.v

ntnoraicnn Arrannfrus.

Sp,eceation of Letters Patent.

Patented Sept.A 3, 1912.

Application led September 18, 1911. Serial No. 649,922.

To all whom t may concern: v

Be it kno-wn thatl, THOMAS, F. CROCKER, a citizen of the United States, residing at Dayton, in the county of Montgomery and State of Ohio, have vinvented'certain new and useful Improvements inElectrical Apparatus, of which the following is a specification.

My invention relates to telephone apparatus of the automatic type, and part-icularly to means for automatically restoring line switches and selector switches which have been accident-ally or abnormally operated cr which have failed to restore by the usualmeans, andis especially designed for use in combinationwith apparat-us o f the Keith system o-f telephony, invented by Alexander E. Keith, but which may be adapted to telephone apparatus of different design.

The object of the invention is to provide such automatic means for restoring abnormally operated line switches, and select-or switches or those regularly operated but which have failed to restore by the usual means, which will not only be simple and cheap in construction, but will be efficient in use, positive in action and unlikely to get out of re air.

lVith the above primary and other incidental objects in view as will morel fully appear in the specification, the invention consists of the features of construction, the means, parts and combinations thereof, and the mode of operation or their equivalents, as hereinafter described and set forth in the claims.

The drawing isa diagrammatic view illustrating so much of a "telephone system of the Keith type as is necessary to illustrate the application o-f the present invention thereto, those portions forming the subjecmatter of the present invention being grouped in the lower right side of the diagram and `:iepaiated from the general or Keith apparatus by a dot and dash line.

For convenience in following the circuits indicated in the diagramfsundry parts have been indicated upon thedrawing by name in addition to the reference characters hereafter employed,- and the resistance of the several coils has-also been indicated on the drawing. c i

There are many conditions under which .the line switches and the trunkswitches of anautomatic telephone system may be abnormally operated, such .as groundedilines,

the jarring of the mechanism during normal operation of the other parts, carelessness of workmen, gusts of wind and other accidental or unnatural means. Under such abnormal operation the plunger of the line switch plunges into the bank terminal as hereafter described, but the I'irstl` selector switch will not operate to select a second selector trunk.

In many automaticl exchangesl several persons are employed whose sole dut-ies are to manuallyrcstore abnormally operated line and first selector switches, or as is commonly termed off normal switches. To obviate such conditions and to provide for the automatic restoration of the abnormally operated switches is one-of the primary objects of the present invention.

' In order that the presentinvention may 75 be more readily understood, the character.- istic features of the portions' of the Keith system to which the present -invention relates will be briefly described.

Referring to the diagram, the line switch illustrated at the upper left portion thereof, comprises a trip magnet 1 and a release magnet 2 arranged at right angles to each other. Below the release magnet 2 is pivoted the release armature 3. This armature 8 carries pivotallyv mounted on its free end a second armature 4 extending upwardly adjacent to, and controlled by the trip magnet l. The trip magnet armature 4 is bent at' right angles at its upper extremity to accom- 9o modate an adjusting screw 5, for the purpose hereafter mentioned. Above the release magnet there is pivotally supported a plunger arm 6 to the end of which is pivotally secured, and fully insulated therefrom, a switch plunger 7 which is adapted, when released, to plunge into and close any one of a series of bank terminals, each comprising four pairs of switchV blades as hereafter mentioned. Nea-r the cent-er of the plunger arm 6 is secured a tension spring 8 the free end of which rests in the adjusting screw stirrup 9. By the adjustment of the screw 5 the tension of the spring 8 may be increased or diminished as required. -It is to 105` be noted that the spring affords the power for tripping the switch plunger 7 into the. bank terminal, and also for withdrawing the plunger from the bankterminal upon the operation of the release magnet. There is `always a downward pull upon. the'stirrup; and when the trip armaturey rests inxnormal 4 switch having no other duty.' than that herei engagement with the plunger arm the pull upon the s'tirrup is transmitted. to the plunger arm on the left of its pivotal connection, 'tending to move the plunger arm in a counter clockwise direction. Then the trip arm is disengaged troni the plunger arm the spring is effective in producing a cloclm 1ise tendency and thrusts the plunger 7 into the bank terminal. The trip armature et provided with a tooth or detent l which engages the end of the plunger arm to hold the arm elevated.

Under normal conditions ol' operation, when the calling` subscriber turns the dial for the first digit of the desired number, the rotary line connector is momentarily grounded at the subscriber@ instrument 11. This ground impulse provides :in energizing circuit 'for the trip magnet extending from the suhscrihers instrument, over the rotary line connector 12, through the bridge cut ott witch 13. the windings of the trip magnet l and through battery to ground at lil. The trip magnet 1 thereupon energizes and. attr-arts the arn'iature 4, .withdrawing the tooth lo trom the end of the plunger arm G,`whicn In response to the spring tension moves about its pivot and thrusts thepliinger 7 intr the terminal bink. When the plunger enters the terminil hanl the two members of each el the t'olowing pairs of contacts are pressed luto engagement with each other; a and afl, D end `51, c and c1, and Z and (Il. lt is assumed igor convenience of explanation that the switch wipe` 15. which is a side switch wiper of the tirst selector in described. is in contact with the first bank contact, and that this contact corresponds with the hanl; terminal sh iwn. lVhen the plunger 7 plunges into the @,)anlr terminal, it closes a circuit through o-b and energizes mechanism not shown which actnates the master switch causing it to move an unoccupied terminal or contact, which operation has no relation zo the present case. The

lalling ol the plunger also closes aa* proriding;` an energizing circuit for the bridge cut oil magnet 1GA which is grounded through bitte jv at 117. The energizing of the bridge out orf magnet attracts the armature thereof, breaking the energizing circuit of the trip magnet l at 13. The closing of the contacts .ff-cl and ./Z Z1 by the plunger extends the calli rihers vertical and rotary line 1 to the trunk conductors yterminati the 'lirst selector switch. no release of the line switch is aecomislicd hy the return of the subscribe1"s to the receiver hook which indimomentarly grounds the release 8 at the first selector. As a result attracting its armature 3 and in turn the trip armature et to permit the release magnet 2 is momentarily ener-v tooth l0 to engage over the 'end of the plunger arm 6. 'Vhen the release magnet 2 demagnetizes, the armatures 3 and el return to normal position, withdrawing the plunger `from the haul: terminal and permitting the bank contacts to disengage. Such is the normal working of the Keith system shown ilrani g However the plunger 7 e to he plunged into the liant: terminal h v some accidental means ietore nientioned,` at a time when the sil ritiene instrument has not. hren operated, and there- 'tore is not restored in the natural manner hv the return of the subscrihers receiver to the hook. therehy renderingl the line ineiiiective :tor a succeedingcall. Under such abnormal condition the operation of the parts as follows: The plunger T having plunged into the bank terminal due to some disturbance or irregularity upon the line, closes the several switches before mentioned forming the bank, energizing the bridge cut oit' magnet 1G to open the trip magnet circuit at 13, connecting the rotary and vertical connectors with the corresponding trunks and the release magnet 2 of the-line switch with the release trunk 1S, permitting current to pass through the release magnet 2 or' the line switch to the tell tale relay 19,- the resistance of which is approximately three thousand three hundred ohms, and thence to ground. operating the tell tale relay 19, but failing to operate the release magnet- 2 because of its low resistancewinding. This is the regular operation of the standard Keith automatic telephone equipment as shown in the drawing, to which the invention forn'iing the subject matter hereof is applied.

:he teit tale relay 19 is grounded through the switch 15 and common line 20 includingcontacts- 2i and 22 to ground at 23. The tell tale relay 19 upon its operation, closes the contact 2l causing current to flow through the first selector release magnet 25 which is grounded through battery at 22,

thence over the connnon line 27 4.hrough the relay 2S and to ground at 29. The release magnet will fail to operate since it wound to but sixtiy ohms resistance while the relay 28 is of three thousand three hun dred ohms resistance. The energization of the relay 28 closes the contact 30 by the incidental attraction of its armaturel and at the same time breaks the contact- 22. The opening of the contact 22 however will not altect the tell tale relay 19 which was previously grounded through this contact 22 to ground at 23, but theftell tale magnet 19 will continue grounded through the common line 20, the resistance coil 31 of one thousand three hundred ohms resistance to ground at 32, thereby causing the tell tale magnet to retain its armature in operated position and the eontacte closed, Vhut any other-line .mined interval of time switch of the section which may be plunged into aterminnl 1bank will not operate its corresponding tell tale magnet because it also would have' to operate through the resistance coil 3l which is o t too great resistance to permit the tell tale relay to attract its arniati'ire while said resistance coil is Yin the circuit; This insures the construction against possible danger of one line switch being cut olf from the telephone action of another if one subscriber should release his trunk switch before the switch l5 shall have shifted to the succeeding contact, sincethe common line may be connected with .but one line switch ata time. The resistance coil 3l ot' the slow acting type is maintained in the circuit until a short period after the iinal release as -hereai'ter described. Upon 'the operation of the relay 28 and the consequent closing of the contact 3U there is grounded at 23 a circuit passing through the contact 30, the contact 33, therelay. 34, the contact 35, thence through the heating /coil ot the tliermostatic time. switch 36 in` 25 the same circuit being oftive hundred ohms resistance, therefore the circuit will be unbroken between grounds 23 and`37, permitting the current to flow through said circuit i .heating the thermostat.

static'bar 'closes the contact 38, thereby short "'fcir'cuiting the heat coil of the ythermostatic until the thermotime switch, whereupon .the entire strength of ci'irreiit is permitted to act upon the relay 34 causing it to attract its armature to malte the contact 39 and` break the contact' 33.

.The contacts 33 and 39 are so'constructed that the armature will make the contact 39 before the contact 33 is broken. Tlieiheat lcoil of the tlierinostatic ,time switch 36 is so wound and the Contact 3S so regulated that an interval of time ofv predetermined length shall elapse between the closingof the cir-- cuit through the heat coil and the short circuiting thereof. In practice it has been found thataninterval offrono ten to twelve seconds will besutlicient.

'The operation of the time switch 36 and the relay 34 closes a circuit from: ground and battery 37through contact 38 excluding the he'a'tcoil of the time switch, through the contact 35, the relay magnet 34, contact 39,

contact 40, vthrough the eoilof the slow acting relay 4l and to ground. at 42. This operation thus far has requireda predeterdependent upon the adj ustnientvof the time switch 36 and con 4tact 38. The relay 41 new operates to close cont-act 43 and at the same time break con tact 44. The closing of the contact 43 by i I the operation of the relay 41 closes a circuit including the slow acting relay 45 and' the time switch, the lcircuit passing froin battery and ground 37 through the thermostat- 36, contact 33, contact and Contact to :the relay 45, 'thence through battery to `iperating t0 attract its several 4opens the contacts 35 and 40 and makes-the 4contactllf'. rlhe opening of the conta-cts 35 and 40 breaks the circuit through the relays i' 34 and 41., allowing the relay 34 to release 'its armature which opens the contact 39 and vremakes the contact 33, whereby currentwillever,

' rent.

Ytests 44 and. 4"( to groundat 43 ing the release magnet 25 or the first/selector ground at 46. The relay will not operate to. attract its armatures however until after the thermostat cools sullciently to open the contact- '38, which will require a period of approximately siitseconds. .Until the voperation of the relay'45, by which several contactsare cout-rolled as hereafter mentioned, current will iow through the relay 41 which is grounded at 42, thence through the contact 40, the Contact 39, previously closed by the relay 34, through said .relay 34, the contact 35 and .the thermostat 36, through batvtery to ground at 3?. The line will also be closed from battery-and ground 37 through contact 35, the contact 43 closed by the slow relay 4l and through the second' slow actin@ relay 45 and battery to ground at 46, but

thebattery at 37 is atf'one end oit said line and the battery 46 at t-lie opposite end of thel line with the relay 45 between yraid' bat- Iteries, the said relay 45 will be inoperative until the thermostat cools suilicient-ly to open the contact 38 which brings the resistance 36 finto the circuit, whereupon the relay 45 will be energized. Theslow acting relay 45 armatures again flow .through thecontact '30 which is grounded at 23 through the-.contact 33, the relay 34, the Contact 43 Which-has not yet been opened due to the slow action of the slow relay 41, and thence through the slow acting 'relay 45 andbattery to ground at 46, thus maintaining the attraction ofthe relay 45 for its armatures. The holding of the contacts bythe relay 45 will be short liowas thecurrent having been interrupted through the relay 41, by the opening of the y contact 40by the relay 45-a-s before .men

tioiied, the said slow acting relay 4l will hold its armature a short time after the current has been so interrupted, continuing to supplycurrent to the slow relay 45 through thecontact 43 as described. .HoweverI when the `vslow relay 41 releases. its armature breaking the conta-et 43,. the current supply to the second slow relay 45 is broken, but saidslow acting relay will continue to attract its armatures maintaining the contact 47 closed andthe contacts 35 and? 40 open for a short time after the relay 41 is demagnetized' to break the supply icur.-

mon line 2.7 will be grounded through conthus` energize y During this latter period. after the action, the courl through the contact 24 closed by the tell tale relay 19 to ground at 26. The energization of the release magnet 25 closes the Contact 49 which grounds the release Vtrunk 18 at 50, thereby energizing` the release magnet 2 of the line switch which is also grounded tl'irough battery. The release magnet 2 thereupon attracts the armature 3 to elevate the tooth l() above the plunger arm preparatory to returning the plunger arm and plunger to normal position upon the fall ot the armature 3 at the demagnetization o't' the release magnet When the slow acting re` lay 45, 'which has held momentarily after its supply current has been broken by the demagnetization o relay ll, releases its armatures the contact 4T is opened, thereby breaking the ground connection of, the common line 2T and selector release magnet 25, which thereupon becoming demagnetized releases its armature breaking the contact 419 and removing the ground connection of the release trunk 18. This causes the demagnetization of the release magnet 2, permitting the armature 3 to fall, restoring the plunger arm and plunger to normal. This completes the cycle of operations by which the abnormally operated plunger is restored to normal. However in addition to the automatic restoring means as described, there 1s provided an automatic alarm which Will give notice ot abnormal operations ot the apparatus in order that the cause of such abnormal operations, sue-h as grounded lines, etc., may be removed. During the period that the contact 38 is closed by the thermostatic time switch a circuit is closed from the ground the contact 35, relay 34 and contact 39 which energizes the slow acting relay 52 which is grounded at 53.

When the contact 38 is broken by the cooling of the theri'nostat as before mentioned, the relay 52 will continue to receive current from battery and ground 46 through relay 45,. contact i-I3, relay 31T', contact 39 and through relay to ground at 53, as long as the slou7 acting relay -i'l continues .to attract its armature. slower action than the relay 45, hence is the last to operate. p close the contact 54 and to break the contact 2l, and being slow actingl retains said contacts in operated 1 osition a short time after the release impulse is sent over the line. The relay 52 serves tivo purposes. It affords resistance in the common line 20, and by closing the contact 54 it closes an alarm circuit .from ground 32 through the said contact 54 to an alarm device 55 which may be either a light, a buzzer or a bell, and thence through battery to ground at 56. l.The alarm 55 gives notice that a line switch is about to be released and it' it does not release. or it it does release and the plunger 7 innnediately drops again as it would in the case of a grounded The relay is adjusted to rlhe relay 52 operates to,

line, the release mechanism would complete a cycle of operations at each operation of the plunger, thereby causing the alarm 55 to give out an intermittent signal.

The automatic releasing system as herein described can be rendered common to any number of line switch trunks. The system cannot possibly interfere with regular calls by prematurely restoring the plunger since the switch 15 Will shift to its succeeding position in the ca se ot' a regular call before the thermostatic time switch 36 shall have oper ated to close the contact 38. A release impulse cannot occur simultaneously with the operation of the plunger 7 because the tell tale relay 19 remains inoperative and does not attract its armature to close the contact 24- .to cause the grounding of the release trunk, tor a predetermined period of time prior to the release of the abnormally operated line switch. The automat-ic release system may be made common to any number of first selector trunks.

A condenser 57 may be bridged around `the contact 47 to avoid a spark upon the operation of said contact.

. While the automatic release system here described is illustrated in connection With the Keith systemV or" automatic telephony and is herein described in such-connection, it is to be understood that it may be applied Vto other systems, Vor may be employed for other analogous purposes, it is therefore not limited to the use and application herein mentioned.

From the. above description it will be apparent that there is thus provided an automatically operating electric system possessing the particular features of advantage loeore enumerated as desirable, but which obviously is susceptible of modification in its Jorm, connections, detail construction and arrangement of parts without departing Having thus described my invention claim:

l. In an electrical apparatus, ,a main circuit, a switch adapted to close the circuit, a switch restoring magnet in said circuit adapted to open the switch, a relay also in the circuit attording such resistance as to normally prevent the operation of the switch restoring magnet at the closing of the circuit, and a supplemental circuit closed by the operation of said relay a slow .acting member in `said circuit adapted. after sistance in the main circuit whereby the restoring magnet will liepermitted to restore sistance in said operation of the restoring switch restoring the switch and open the main circuit.

2. In an electricalapparatus, a main c1rcuit, a switch adapted to close said circuit,-

a switch restoring magnet in said circuit, re-

circuit adapted to prevent the operation of the switch restoring mag net, and means including a slow acting switch energized by the closing kof the main circuit for removing said resistance from the circuit, to permit the operation of the` switch restoring magnet after the elapse of an interval of time from the closing of the main circuit. Y l 3. In an electrical apparatus, a main circuit, a switch adapted to close the circuit, a switch restoring magnet in said circuit, a relay energized by the closing of nsaid circuit by the switch, but normally preventing the magnet, asupplemental circuit closed by the operation of said relay, a thermostatic switch in said circuit adapted by its operation to causethe relay of the main circuit to bel short circuited, thereby permitting the operation of the magnet. 4C. In an electrical apparatus, a main circuit, a switch adapted to close the circuit, a switch `restoring magnet in said circuit, a ,second circuit closed by the operation of the relay of the main circuit, a magnet in said Second circuit ada ted upon operation to close the main circuit in such Way as to energize the restoringvmagnet, a relay also in said second circuit affording such resistance as to prevent the operation ofthe circuit closing magnet, a third circuit closed by the relay of the second circuit, a relay in said third circuit, and the heat coil of a thermostatic switch also in said circuit and aord-l ing such resistance that'the relay will not operate unt-il the heat coil is removed from the circuit, uthe said thermostatic switch being adapted to short circuit the heat coil after an intervalv of time from vthe closing of the circuit, thereby permitting the operation of the third circuit relay, which closes a succeeding circuit, a slow acting relay in the succeeding circuit which after the elapse of a'n interval of time acts to exclude the resistance from the second circuit mentioned permitting the second circuit magnet to op erate to exclude the resistance from the main circuit enabling the restoring magnet to retract the switch. 4

5. In an electrical apparatus, a main circuit, a 'switch adapted to close said circuit,

switch restoring magnet in said circuit, ree,

,'fsistance in said circuit normally preventing the operation of the restoring magnet, and

means including a slow acting electrically controlled member for automatically removing the resistance from the circult after the of an interval: of time Alitem-"the (2i-'losping ci the .circuit whereby the restoring a switch restoring magnetin said'circuit rev sistance thev'operation of the restoringy magnet a slow acting electrically controlled member energized through the closing of said circuit 4adapted by its operation to exclude the resistance from the restoring magnet circuit whereby the said magnet will operate to retract the switch, and a second slow acting electrically controlled member operating,

subsequent to the operation of the last mentioned slow acting member, to open the circuit to demagnetize the restoring magnet.

7. In an electrical apparatus, a main circuit, a switch adaptedvto close said circuit, a switch restoring magnet, a relay in the clrcuit with the magnet aording such resistance as to normally prevent the ,operation of the magnet, a lsecond circuit, ar'rilagnet therein adapted to close an operating'circuit through the restoring magnet, a relay also in said second circuit iaifording such resistance as to normally prevent the operation of said circuit closing magnet, a third circuit closed by the operation of the second circuit relay, a relay in said circuit and an electrically controlled slow acting member affording such resistance as to prevent the operation of the relay untill after the operation of said slow acting member, whereupon the third circuit relay operates to remove the resistance from the second circuit enabling the circuit closing magnet to operate to close an energizing circuit through the restoring magnet, and means to' automatically break said circuit.

8. In an electrical apparatus, a main circuit, a switch adapted to close said circuit, a switch restoring magnet, resistance in the circuitl normally' preventing the operation of the magnet, a second circuit having a magnet therein adapted upon operation to close an energizing circuit through, the switch restoring magnet, resistance in said circuit normally preventing the operation of said magnet, and a slow acting electrically controlled member energized through the clos ing of the switch, and adapted by its operation to cause an energizing current to flow' through the circuit closing magnet of the second circuit, which in turn will cause an energizing circuit to iiow through the switch restoring magnet, and means for automatically breaking the said circuit after'an interval of time.

9. In an electrical apparatus, a main cir cuit, a switch 'therein' a switch restoring magnet, a slow acting electrically controlled member energized by the closing of the main in the circuit normally preventing circuit switch adapted to close an energizing circuit through the switch restoring magnet after the elapse of an interval of time from the closing of the switch, and means to automatically break said circuit.

10. In an electrical apparatus, a main circuit, a switch therein, a -sloW acting electrically controlled restoring member energized by the closing of said main circuit switch adapted to open said switch after the lapse of an interval of time from the closing thereof, said restoring member 'being denergized through the opening of said .11min circuit, substantially as specified.

In testimony whereof, I have hereunto set my hand this 11th day of September 1911.

THOMAS F. CROCKER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

